All Day Bay Swell Statistics, Autumn: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at All Day Bay that coincided with light winds or offshore conditions over a normal southern hemisphere autumn and is based upon 6580 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow illustrate increasing swell sizes and red shows largest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the prevailing swell direction, shown by the longest spokes, was SSE, whereas the the most common wind blows from the NW. The chart at the bottom shows the same thing but without direction information. For example, swells larger than 1.5 feet (0.5m) coincided with good wind conditions 37% of the time, equivalent to 34 days. Open water swells exceeding >3m (>10ft) only arise 1.6% of the time in a typical southern hemisphere autumn, equivalent to just one day but 9% of the time we expect swell in the range 2-3m (6.5-10ft) 9%, equivalent to (8 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that All Day Bay is exposed to open water swells, we estimate that clean surf can be found at All Day Bay about 37% of the time and that surf is spoilt by onshore wind 31% of the time. This is means that we expect 62 days with waves in a typical southern hemisphere autumn, of which 34 days should be surfable.
IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.